Collision Problem-How to keep character on varying ground levels?!!!

Blitz3D Forums/Blitz3D Programming/Collision Problem-How to keep character on varying ground levels?!!!

KovaSteel

(Posted 2003) [#1]

While programming the controls for my game ,i got stuck on a collision problem which is pestering me for some times!!! Please help!

How can i keep my character walking on the ground of my level(created in a modelling package,so it is not a terrain)??!!When the height of the ground is the same everywhere,there`s no problem since i can position the character on it(Like PositionEntity character,0,fixedheightofcharacterabovegroud,0) and everything will work ok. But when it comes to varying gound levels,like climbing stairs or crossing bridges,then it gets messy. I tried this after some tries but it didn`t work(This code is ONLY only for lowering the character`s heigt):

y#=character current height
Entitytype character,1
Entitytype level,2
If Not(Entitycollided character,2) then Positionentity character 0,y#-.1,0

I first thought that it would test to see if the character is touching the ground and then reduce it`s height until it does but unfortunately it isn`t working. My character is half in the ground when i use this but when i walk DOWN the stairs. My characters height about the ground is reduced to that of the stairs but my character still half stuck in the ground. Please help!!!!!!

Shambler

(Posted 2003) [#2]

I just do a linepick straight down and alter the players position based on the PickedY#() and the players YPosition.

This way you can smooth out stairs so the camera doesn't bump up and down them.

LinePick EntityX#(p\head,True),EntityY#(p\head,True),EntityZ#(p\head,True),0,-50,0

currentheight#=EntityY#(p\head,True)-PickedY#()
currentpicked=PickedEntity()

If currentpicked<>0
If currentheight#<p\height#
MoveEntity p\head,0,(p\height#-currentheight#)/10,0
EndIf
If currentheight#>p\height#
MoveEntity p\head,0,-(currentheight#-p\height#)/5,0
EndIf
EndIf

Rob	(Posted 2003) [#3]

works for me...

;set up variables
Const c_player=1,c_level=2
Global player_radius# = 0.2
Global player_height# = 0.4
Global player_step#   = 1
gravity#=0
vx#=0
vy#=0
vz#=0


;create display
HidePointer
Graphics3D 640,480,16,2
camera=CreateCamera()

CameraRange camera,0.1,1000

;load files
level=LoadAnimMesh("temp.b3d")
playerpivot=CreatePivot();Sphere():EntityColor playerpivot,255,0,0:EntityAlpha playerpivot,0.25:EntityFX playerpivot,1

;set up scene
light=CreateLight(1)
TurnEntity light,45,0,0
LightColor light,128,128,128

light=CreateLight(1)
TurnEntity light,-45,180,0
LightColor light,64,64,128


;position player
PositionEntity playerpivot,0,50,0
ScaleEntity playerpivot,player_radius,player_height,player_radius

;set up collisions
EntityType playerpivot,c_player
EntityRadius playerpivot,player_radius,player_height

EntityType level,c_level,1
EntityPickMode level,2

For i=1 To CountChildren(level)
	EntityPickMode GetChild(level,i),2
Next
	

Collisions c_player,c_level,2,2

AmbientLight 80,80,80


;set up chase cam
PositionEntity camera,EntityX(playerpivot),EntityY(playerpivot),EntityZ(playerpivot)
PointEntity camera,playerpivot
MoveEntity camera,0,player_height,0
EntityParent camera,playerpivot


While Not KeyHit(1)
	UpdateWorld
	RenderWorld
	Gosub physics
	MoveMouse 320,240
	Flip
Wend
End

.physics:

	;physics
	vxspd# = 0.025
	vyspd# = 0.05
	vzspd# = 0.025
	inertia# = 0.8
	gravity# = -1
	mousedampx#=0.15
	mousedampy#=0.12
	
	;input
	impulseforward = KeyDown(17)
	impulseback = KeyDown(31)
	impulseleft = KeyDown(30)
	impulseright = KeyDown(32)

	mxspd#=-MouseXSpeed()*mousedampx
	myspd#=MouseYSpeed()*mousedampy

	TurnEntity camera,myspd,0,0

	;impulse
	If impulseforward vz#=vz+vzspd
	If impulseback vz=vz-vzspd
	If impulseleft vx#=vx-vxspd
	If impulseright vx=vx+vxspd
	


	;inertia and gravity
	vx=vx*inertia
	vy=vy/2
	vz=vz*inertia
	
	TurnEntity playerpivot,0,mxspd,0
	MoveEntity playerpivot,vx,vy,vz

	
	;stairclimbing
	oldx#=x#
	oldy#=y#
	oldz#=z#
	x#=EntityX(playerpivot)
	y#=EntityY(playerpivot)
	z#=EntityZ(playerpivot)


	pick=LinePick(x,y,z,0,-player_step,0,1)
	

	
	If pick
		slope# = 1.0-Abs(PickedNY()) *.025

		If EntityY(playerpivot)<PickedY()+player_step
			vy=vy+vyspd
		EndIf

	Else
		vy=vy-vyspd
	EndIf

	
	TranslateEntity playerpivot,0,vy,0


Return

KovaSteel

(Posted 2003) [#4]

Thanks!i`ll try these methods!